| Microwave-vacuum (MV) drying is a new technology at present, except for wood industry, which has been widely used in many aspects, such as food industry. The paper related to the fundamental law and mechanism of wood drying under microwave-vacuum was seldom published. In this thesis, under MV, the drying characters of wood using Masson pine as experimental material has been systematically researched and concluded, the mechanism of heat and mass transfer in wood has been described, and the mathematic model based on the theory of heat and mass transfer has been developed. The research will provide a theory basis for the further application of MV drying technology in wood industry. The main conclusion and originality can be showed as the following:1. Based on the theory analysis, the microwave penetration depth in wood was calculated.2. The drying characters of wood under MV has been systematically analysis and concluded, based on a lot of experiences. The results show :①.the average drying rate of wood increases with the increase of microwave input power, wood initial moisture content and vacuum level; ②.the effects of thickness and length of wood on the average drying rate of wood is not significant;③.the rate of moisture transfer varies with the direction of moisture transfer or grain direction of wood, and ranks as the following sequence: unsealed sample > longitudinal > radial > tangential;④.the result of variance analysis proved that the other factors except for microwave input power density and wood initial moisture content un-significantly affect on the average drying rate of wood;⑤. The whole drying process of wood can be divided into three distinct periods: the first one, the temperature of wood increase sharply and drying rate of wood increases gradually to reach a plateau; the second one, the drying entered a constant temperature and drying rate period; the last one, the drying entered a heating up period in which drying rate decrease slow and the temperature started to increase again;⑥.during MV drying of wood, per 1 kilogram watt microwave input energy, moisture with a mass of 0.7 to 1.2 kilogram can be removed from wood, and the microwave energy efficiency of the drying process significantly increase with the increase of vacuum level and wood initial moisture content;⑦MV drying can produce high drying rate, which is at least 4 times higher than that achieved in floating pressure drying.3. The effect of microwave treatment on the ability of moisture transfer through wood has been researched, based on experiments and theory analysis. The results show: microwave treatment was able to damage effectively the pit membrane structure of wood, improve permeability coefficient, and speed the drying rate of wood in which moisture permeability can be considered to be predominant mass transfer; but, compared with that of untreated wood, moisture diffusion coefficient of microwave pretreatment wood was increased by below 3 percent, which was not able to improve significantly the sequence drying process during conventional drying.4. The study was conducted to investigate the effect of thermal diffusion on moisture transfer. The result shows: moisture fluxed into the wood from the warm surface to the cold surface even if opposite faces of the sealed wood assembly were exposed continuously to different but constant temperature for a short period, the absolute value of the ratio of the moisture content gradient to the temperature gradient(dM/dT) is below 0.9%/°C; During the drying process of MV, for the whole board, the effect of thermal diffusion on moisture movement is not significant, but it can cause a leveling of moisture profile in a local range of wood.5. The mechanism of moisture transfer during MV drying has been firstly systematically revealed, and its mathematic model has been established. The results show:①.at the rational microwave input power density and wood thickness range, the temperature and moisture distribution in wood is uniform, and the latter is more uniform in the last period of dry...
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